The present invention relates to a variable-light-beam-pattern four-lamp type headlamp system having two lamps mounted on each side of a vehicle.
A headlamp system has been known in which, to illuminate the road in wet weather, as shown in FIG. 11, the central axis of the light beam is inclined downward or obliquely downward with respect to its angle for normal illumination with its cutoff maintained unchanged. In a headlamp of this type, the light beam for illuminating the road is obtained, for instance, by inclining the central axis of the reflector of a projection lamp with respect to the center O of the light distribution pattern.
In wet weather, the light beam of the above-described headlamp is deflected downward and/or downward and sideward so as to better illuminate the near part of the road. As a result, the distant part of the road (indicated by an arrow A) is lower in luminance. Thus, the distant part is lower in visibility, and the side of the road (indicated by an arrow B), which is opposite to the side to which the light beam has been deflected, is also lower in luminance. Accordingly the visibility is often insufficient when the vehicle turns to the right.
Moreover, since the conventional headlamp is intended to provide the necessary luminance with only one lamp, the power consumption of the light source, namely, the light bulb, is large, 50 to 80 W, and therefore a large load is imposed on the electrical system of the vehicle.